Conveyors used for transporting objects, such as boxes, are heretofore known. Such conveyors generally comprise a plurality of rods having freely turning rollers or skate wheels, which define a path or surface for movement of the objects, and a support structure, which enables the length and curvature of the conveyor to be selectively varied. The conveyors can be used to transport objects horizontally and up and down inclines. Some conveyors are supported by a plurality of legs having wheels or casters to provide portability.
Attempts have been made to power the conveyors in order to provide a more effective transporting system. Some conveyors having fixed lengths and linear paths employ individually powered rollers, but these conveyors have limited utility because the distance and path needed to transport materials frequently varies from job to job. Powered conveyors having flexible lengths and paths are more useful, but flexible powered conveyors have not been entirely successful. For example, some flexible powered conveyors use rollers rotatably driven by O-ring or chain drive systems which connect multiple rollers together to multiple external power sources, typically motors mounted on legs of the conveyor. The primary disadvantage of these drive systems is that, when one of the driven rollers is experiencing a heavy load that reduces its rotational speed, power losses are transmitted to all of the other powered rollers connected to the same O-ring or chain. Typically, a roller located on an incline may experience a loss of rotational speed as it transports a heavy box, which likely will cause reductions in the rotational speeds of the other rollers. This slows movement of the other boxes along the conveyor and may cause an undesirable accumulation of boxes at the slow spot on the conveyor.
Yet another problem with the O-ring and chain systems is that the O-rings and chains tend to be long and difficult to keep from tangling without extra hardware, particularly when curved, expanded, or contracted. Another shortcoming of the chain drive systems is that they usually are very difficult and expensive to maintain.